rsync_backup

A single-file Bash script for versioned rsync backups, with an interactive menu, cron scheduling, and checksum-based change detection — no dependencies beyond bash, rsync, and cron.

Features

• Menu-driven — add/remove source directories, set a destination, run backups, manage cron, and view logs, all from one interactive menu.
• Checksum-based sync — uses rsync -c to compare files by checksum rather than size/mtime, so a touched-but-unchanged file is correctly skipped.
• Simple version control — before any file is overwritten because its checksum differs, the previous copy is moved into a timestamped .versions/<run-timestamp>/ folder (via rsync --backup --backup-dir), preserving its relative path. Empty version folders from no-op runs are pruned automatically.
• Cron integration — install, inspect, or remove a scheduled run (hourly, daily at a set time, every N minutes, or a custom cron expression) directly from the menu.
• Headless mode — ./rsync_backup.sh run performs a backup non-interactively using the saved config, for use in cron or CI.
• Logging — every run appends to ~/.config/rsync_backup/backup.log, including per-directory sync results and skips.

Requirements

• Bash
• rsync
• cron (only needed if you use the scheduling feature)
• macOS or Linux (see Platform notes below)

Installation

curl -O https://raw.githubusercontent.com/alexadsett/rsyncbackupscript/main/rsync_backup.sh
chmod +x rsync_backup.sh

Or clone the repo and run it from there directly.

Usage

Interactive menu

./rsync_backup.sh

   1) Add a directory to back up
   2) Remove a directory
   3) List directories
   4) Set destination root
   5) Run backup now
   6) Install / update cron schedule
   7) Show current cron schedule
   8) Remove cron schedule
   9) View recent log
   0) Exit

1. Set a destination root (option 4) — e.g. an external drive or mounted backup volume.
2. Add source directories (option 1) — each is mirrored under the destination at its own full path (DEST_ROOT + source path), so multiple sources never collide.
3. Run a backup (option 5), or install a cron schedule (option 6) to automate it.

Headless / cron mode

./rsync_backup.sh run

Runs a backup using the existing config with no prompts — this is what the cron installer wires up for you automatically, but you can also call it directly from your own scripts or CI.

Configuration

All state lives under ~/.config/rsync_backup/:

File	Purpose
dirs.list	One source directory per line
settings.conf	Stores DEST_ROOT
backup.log	Timestamped run history

How versioning works

Each backup run gets a timestamp, e.g. 2026-07-13_143000. When a file's checksum differs from what's already at the destination, rsync saves the old version to:

<DEST_ROOT>/.versions/<run-timestamp>/<original path>

before overwriting it with the new one. Unchanged files are left alone and produce no version entry. This gives you a lightweight history of every file that ever changed, without a full second copy of unchanged data each run.

Cron scheduling

Option 6 in the menu offers:

1. Every hour
2. Every day at a specific time
3. Every N minutes
4. A custom 5-field cron expression

The job is installed with a marker comment (# rsync_backup_auto_job) so the script can find, replace, or remove only its own entry without touching the rest of your crontab.

Platform notes

• The script uses BSD sed syntax (sed -i '') in remove_directory, which is macOS's native sed. On Linux, change that line to sed -i "${num}d" "$DIRS_FILE" (GNU sed doesn't take the empty backup-suffix argument).
• The macOS cron note baked into the installer applies if you're on macOS: grant Terminal (or whatever runs cron) Full Disk Access under System Settings → Privacy & Security, or scheduled runs may silently fail to read source directories.